Correlation Coefficient Quiz

Which of the following statements is false?

• The coefficient of determination can have values from –1 to 1.

• The coefficient of determination can be applied to any curve.

• The coefficient of determination can be applied to any straight line.

• The coefficient of determination is the variation in y explained by variation in x, divided by the total variation in y.

• The magnitude of the correlation coefficient determines the strength of the linear relationship

• The sign of the correlation coefficient determines whether the relationship is positive or negative

A hi-fi store kept track of the number of advertisements it placed in local newspapers and the number of stereo systemsit sold each week.Week 1 2 3 4 5 6 7 8Advertisements, x 6 5 3 2 1 4 3 2Stereos Sold, y 20 15 12 8 6 7 9 7i. What is the correlation coefficient for the set of data?ii. What does this correlation coefficient suggest about the effectiveness of the advertisements?

A manufacturer of flexible seals for industrial equipment tests samples of its seals at a variety of temperatures andcollects the following data.Temperature (ºC) 16; 5; 9; 12; 7; 10Seal Failures 3; 12; 8; 6; 4; 7a) Construct a scatter plot for these data.b) Identify any outlier(s) and explain your choice(s).c) Calculate the correlation coefficient for this data.

A car safety association conducted tests to measure the stopping distances of a new model of car and collected thefollowing measurements.Speed (km/h) 30; 40; 50; 60; 70; 80; 90; 100Stopping Distance (m) 19.2; 22.2; 24.8; 27.1; 29.5; 31.6; 33.2; 35.0a) Construct a scatter plot for these data.b) Identify any outlier(s) and explain your choice(s).c) Calculate the correlation coefficient for this data.